OBJECTIVE: To compare serum retinol levels in preschool children during an episode of pneumonia and 45 days after the resolution of the infection. METHODS: The study was conducted with preschool children without any infection (control group, n = 9) or children hospitalized for pneumonia (n = 12), who were evaluated soon after hospitalization (phase 1) and 45 days later (phase 2). Nutritional assessment included anthropometric measurements, a food questionnaire, and laboratory blood routine examination, including urinary and serum retinol levels. Paired Student t or Mann-Whitney tests were used as required. RESULTS: Food intake was similar between groups. Blood hemoglobin and serum sodium and albumin decreased during phase 1, while there were higher C-reactive protein serum values. Urinary retinol levels remained unchanged whereas serum retinol increased significantly after pneumonia recovery. CONCLUSIONS: During the course of pneumonia, children had transient decrease in serum levels of vitamin A, an epiphenomenon of the acute phase response.